Thank you for the clarification.
Initially we were thinking that such a control is not applicable in the context of Windows Phone, having in mind the predefined keyboard layouts that may be specified on a per textbox basis.
The latter however will not prevent you to enter more characters or to force the user observe a predefined pattern. So, we will add this new control in our backlog and will do our best to implement it either for Q1 2012 or for one of the service packs afterwards.
I would like to thank you for your valuable feedback - I have updated your Telerik points for your time.
the Telerik team
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